Art of producing propeller blades



A ril 20, 1948. B, STULEN 2,440,127

I ART OF PRODUCING PROPELLER BLADES Filed July 31, 1944 4 Sheets-Sheet 1 F, B. STULEN ART OF PRODUCING PROPELLER BLADES 4 Sheets-Sheet 2 Filed July 3]., 1944 orneg April 20, 1948. F. B. STULEN 2,440,127

ART OF PRODUCING PROPELLER BLADES Filed July 31, 1944 4 Sheets-Sheet 3 lead!) eaqe a Jm 1e er hdel? I! 23 ll I: la ,0

in I 2/ [a f2 27 l7 Snuentbr G ton-neg April 9 8- F. B. STULEN 2,440,127 I ART 03 rnonucma PROPELLER BLADES Filed July 31, '1944 4 Sheets-Sheet 4 Monitor Patented Apr. 20, 1948 ART OF PRODUCING PROPELLER BLADES Foster B. Stulen, West Orange, N. J., assignor to Curtiss-Wright Corporation, a corporation of Delaware Application July 31, 1944, Serial No. 547,463 1 Claim. (Cl. 29-156.8)

My invention relates to the art of producing propeller blades,

In accordance with the invention, a propeller blade or blade construction, formed from a plurality of shaped members which have been bonded together, has twist imparted thereto at least in the range from approximately zero twist to final twist to thereby produce a propeller blade having final profile and final twist.

More particularly, the aforesaid twist-imparting operation involves elevation in temperature of the blade construction and the subsequent sublection thereof to a shaping operation while maintaining the interior blade construction chamber under gas pressure substantially higher than that of the atmosphere.

Various other objects, advantages and features of my invention will become apparent from the following detailed description,

My invention resides in the art of producing erations in order to produce the complete plates C and T illustrated in Figs. 3-6 inclusive. Thus, each plate Cl and TI is milled to produce a plane tapered plate. Thereupon, the plate edges are angularly displaced and each plate is subjected to a final milling operation. At this time, the plates are trimmed and then shaped in dies such as 11- lustrated in Fig. 30 of Letters Patent No. 2,263,425 to impart all of the twist to the plates and to give them their final profile. Finally, after minor milling operations, the plates 0 and T of Figs. 3-6 inclusive are produced.

As shown in Fig. 3, the camber plate C comprises a tubular shank I which comprises a ring I a and which has the convex plate section 2 extending therefrom, Figs, 4, 5 and 6. The thrust plate T substantially closes the opening defined propeller blades as hereinafter described and claimed.

For an understanding of my invention, reference is to be had to the accompanying drawings, in which:

Figures 1 and 2 are plan views showing plane plates destined tobecome the two plates of a propeller blade;

Fig. 3 is a plan view showing a propeller blade Figs. 4, 5 and 6 are transverse, sectional views taken on the respective lines 4-4, 5-5 and 8-6 of Fig. 3 looking in the direction of the arrows;

Figs. 7 and 8 are plan and elevational views, respectively, showing a die arrangement for imparting twist to a propeller blade;

Fig. 9 is an enlarged longitudinal sectional view taken on the line 9-9 of Fig. 7 looking in the direction of the arrows and Figs. 10, 11 and 12 are transverse sectional views taken on the respective lines I Il-l 0, I l--l| and lZ-IZ of Fig. 7 looking in the direction of the arrows.

In general and for purposes of explanation, .I have illustrated and described a propeller blade having final pitch of one hand and have described an arrangement for causing the propeller blade to have final pitch of the opposite hand. As hereinafter stated, however, the invention is not to be thus limited.

Referring to Figs. 1 and 2, I have shown plane sheets of metal Cl and TI destined to form the plates of a propeller blade having final pitch of one hand as aforesaid. As described in U. S. Letters Patent No. 2,214,338 and No. 2,263,425, these plane sheets of metal are subjected to various opby the camber plate C and the two plates C and T are secured together by weld metal 3 as illustrated, to form a propeller blade or blade construction P, the slot in the tubular shank I also being closed by weld metal 3. I

The aforesaid shaping dies are of such character that they impart twist and profile to the plates C and T causing the resulting propeller blade or blade construction P to have left hand pitch as indicated in Figs. 4, 5 and 6 where the lines L indicate the reference plane and the lines Ll are chord lines. In accordance with the invention, the propeller blade or blade construction P is subjected to an operation whereby the pitch thereof is changed from that of the left hand to that of the right hand.

To this end and in accordance with the invention, I may utilize a suitable press or blow-up die as known in the art and shown in Figs. '7, 8 and 9 as comprising a lower die structure 6 suitably anchored in fixed position together with an upper die structure 1 connected to suitable hydraulic mechanism, not shown, utilizable for raising and lowering the same. As illustrated, the die, structures 6 and l comprise suitable chambers 8 into and through which cooling water is circulated by pipes 9. The die structures 6 and l cooperate,

when closed, to form an interior chamber l0 shaped to impart twist of the right hand to a propeller blade,

With the form ,of the invention herein disclosed, the die structure 6 forms the camber surface of the propeller blade to which twist is to be imparted and, as the tip of the die is faced, the leading edge surface of the die is toward the right and the trailing edge thereof is toward the left.

When twist of the right hand is to be imparted to the propeller blade P (which has twist of the structure 8, after elevation of the upper die structure I, with the thrust plate '1 facing downwardly and with the leading edge thereof at the left when facing the tip of the die. when the propeller blade P is thus positioned, the lower part of the ring la occupies that part of a channel II which is formed in the lower die surface. At this time, the upper die structure I is moved to its lower operative position and, in so doing, the upper part of the ring la is caused to occupy that party of the channel Ii which is formed in the upper die surface. In this position, the extreme shank end of the propeller blade P projects beyond the cooperating die structure to a slight extent as illustrated in Fig. 9.

Prior. to the time that the thus positioned in the press, the temperature thereof should be elevated in suitable manner into a range from 1600 F. to 1700 F., more or less. Furthermore, at this time, there should be available a source of air under pressure of approximately 900 pounds per. square inch which is made efiective interiorly of the hollow propeller blade during the shaping operation.

Accordingly, it is necessary to seal the otherwise open end of said propeller blade P and, for

this purpose, an arrangement of any suitable character, for example, as known in the art may be employed. However, preferably, I utilize a sealing arrangement of the character disclosed in U. S. Letters Patent No. 2,350,541.

Briefly, as herein shown, a sealing arrangement of this characer comprises a vertical pin l2, Fig. 7, carried by a lug extending from the lower die structure Ii. This pin l2 pivotally supports a supporting member l3 which, at its opposite end, comprises a notch with which is coactable a latch it having an actuating handle [5.

As illustrated in Fig. 9, 13 comprises a, central passage longitudinally alined, when said supporting member i3 is in its closed position, with the chamber In of the press. The neck of a circular chamber-forming structure It extends through this central passage and is engaged by a nut l1 to thereby secure the structure It to the supporting member l3.

A tubular memberifl is disposed on the structure l6 for free slidable movement. The circular flanged section 19a of a cap member [9 is threaded to one end of the member 18, said cap member l9 being slidable in a channel formed at one end of the structure 16 to the extent permitted by spaced stop surfaces formed on said structure It and the supporting member l3. The other end of the member it comprises an integral, inwardly extending flanged section I80. having a centrally disposed tubular section l8b extending to both sides thereof, said tubular section 18b being alined longitudinally with the interior chamber l0. Suitably secured to the exterior surfaces of the flanged section Ida is a plate 2| having a central passage in which one end of the tubular section I8!) is snugly received. As shown in Fig. 9, a ring-like gasket 22 is disposed in a channel provided therefor in the plate 2|.

The aforesaid structure [6 comprises an inwardly extending flanged section defining an inner circular opening. Suitably secured, as by screws 23, to said flanged section is a clamping ring '24 and the base of a sealing cup 25 which slidably engages the interior surface of the member IS in sealing relation.

Disposed :between memoir of the structure it and the tubular section lab is a helical spring propeller blade P is the supporting memberand all parts carried thereby in adirection from left to right. Fig. 9.

Associated interiorly and in threaded relation with the neck of the structure It is a conduit extension 21a of a channel-forming structure 21 with which is associated one end of a pipe 2' leading to the aforesaid source of air under pressure.

Assuming that the supporting member I! is in its open position and that the die structure 0 is in its upper position. a left hand propeller blade P of the character shown in Figs. 3-8 inclusive, after the temperature thereof has been elevated as described, is disposed upon the die structure 8 whereupon the press is actuated to move the die structure 7 to its lower position. Thereupon, the member I 3' is moved to its closed position and latched to positively seal the hollow chamber of the propeller blade P.-. At this time, air under pressure, as described, is-admittedthrough the pipe 28 and cooling water is circulated through the pipes 9. As the shaping-setting operation proceeds, the die structures. cause the blade surfaces to take a set configuration corresponding to the configuration thereof, such blade surfaces being interiorly supported by the air under pressure. After a suitable period has elapsed such, for example, as several minutes, the operation is completed whereupon the source of air is disconnected, the member l3 is moved ,to its open position, the die structure I is elevated and the propeller blade Pl removed from the blow-up die, said blade Pl now having its final profile and twist of the right hand.

Although the invention has been described in connection with a method of altering the pitch of apropeller blade involving changing the pitch thereof from that of the left hand to that of the right hand, it shall be understood that the invention is not to be thus limited. In practicing my invention as disclosed, the pitch of the propeller blade is changed to or passes through zero pitch as indicated by the reference plane L and then to final pitch as indicated in Figs. 10, 11 and 12.

In a broader phase, then, my invention relates to a method of imparting twist to a propeller blade or blade construction at least in the range from approximately zero twist to final twist.

In view of the foregoing description, it will be understood that the method of my invention is practiced on a propeller blade or blade construction formed from a plurality of members which, after suitable shaping operations, are bonded together to produce the described propeller blade or blade construction. Initially, these members may be and preferably areplane plates; as such, they may be shaped in an advantageous manner and, subsequently, the individual members may readily have the desired profile imparted thereto. The utilization of a plurality of shaped members,

then, facilitates the efficient production of a pro-' peller blade or blade construction of the character described.

An incomplete propeller blade or blade construction is symmetrical when its external surfaces are disposed symmetrically with respect to .some plane which extends longitudinally of the blade construction. This symmetrical relation obtains by reason of the fact that any line extending perpendicular to the aforesaid plane (of symmetry) and intersecting one side of the blade construction has the same length, between said plane and the point of intersection, as the length of a straight-line extension of said line between said plane and the point of intersection thereof with the opposite side of said blade construction.

An incomplete propeller blade or blade construction is non-symmetrical when its external surfaces are disposed non-symmetrically (instead of symmetrically as described above) with respect to any and all planes which extend longitudinally of the blade construction. It is well known in the art that completed propeller blades are nonsymmetrical principally for aerodynamic reasons and, in the form of the invention herein disclosed,

the propeller blade P having pitch of the left hand and the propeller blade Pl having pitch of the right hand are both non-symmetrical. This condition exists principally by reason of the fact that the configuration of the thrust plate of each propeller blade diflers from that of the conflg uration of the camber plate of each propeller blade in that the thrust plates are-less curved (more plane) than the camber plates. Although the invention has been described with respect to non-symmetrical blades, it shall be understood that it is not to be thus limited since, as'well, the invention is likewise applicable tosymmetrical propeller blades as described above.

,wnue the invention has been described with respect to a certain particular preferred example which gives satisfactory results, it will be understood by those skilled in the art-after understanding the invention, that various changes and modiflcations may be made without departing from the spirit and scope of the invention, and it is intended therefore. in the appended claim to cover all such changes and modifications.

cured by Letters Patent is:

In the art of producing a volving shaping, trimming and attachment together of separate plate members by a bonding operation contiguous to the blade leading and trailing edges to thereby produce and substantially complete insofar as blade airfoil section is concerned and except for final twist, a propeller blade having twist of one hand. the steps which consist in heating the propeller blade, and changing the twist of said propeller blade throughout its length from that of said one hand to that of the opposite hand in response to a shaping operation performed on the propeller blade while maintaining the interior chamber thereof under gas pressure substantially higher than that of the atmosphere.

FOSTER B. STULEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,909,097 Damerell May 16, 1933 1,927,247 Squires Sept. 19, 1933 r 2,007,776 smith July 9, 1935 2,012,389 Heath Aug. 27, 1935 2,214,338 McKee 'Bept. 10, 1940 2,231,772 Nelson Feb. 11, 1941 2,263,425 McKee Nov. '18, 1941 2,350,541 Stulen June 6, 1944 FOREIGN PATENTS Country Date propeller blade in Great Britain Oct. 1, 1934 

